Method and device using rotating printing arm to project or view image across a workpiece

ABSTRACT

The technology disclosed relates to scanning of large flat substrates for reading and writing images. Examples are flat panel displays, PCB&#39;s and photovoltaic panels. Reading and writing is to be understood in a broad sense: reading may mean microscopy, inspection, metrology, spectroscopy, interferometry, scatterometry, etc. of a large workpiece, and writing may mean exposing a photoresist, annealing by optical heating, ablating, or creating any other change to the surface by an optical beam. In particular, we disclose a technology that uses a rotating or swinging arm that describes an arc across a workpiece as it scans, instead of following a traditional straight-line motion.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/200,970, entitled, “Method and Device Using RotatingPrinting Arm to Project or View Image Across a Workpiece,” filed on Dec.5, 2008.

BACKGROUND OF THE INVENTION

The technology disclosed relates to scanning of large flat substratesfor reading and writing images. Examples are flat panel displays,Printed Circuit Boards (PCBs) and photovoltaic panels. Reading andwriting is to be understood in a broad sense: reading may meanmicroscopy, inspection, metrology, spectroscopy, interferometry,scatterometry, etc. of a large workpiece, and writing may mean exposinga photoresist, annealing by optical heating, ablating, or creating anyother change to the surface by an optical beam. In particular, wedisclose a technology that uses a rotating or swinging arm thatdescribes an arc across a workpiece as it scans, instead of following atraditional straight-line motion.

FIG. 1 shows one variety of prior art scanning systems. A flat workpiece110 is placed on a stage 120 and a writing or reading head 130 isscanned across it. The stage 120 advances the workpiece 110 in onedirection as the head 130 scans in a perpendicular direction. A finallens 150 may be placed between the head 130 and workpiece 110. Othersystems have a stationary workpiece and a scanning head that moves alongperpendicular axes, such as x-y axes. Still other systems have astationary scanning head and a stage that moves along perpendicularaxes. Each of these architectures has its own mechanical characteristicsthat impact its effective scanning speed.

For instance, a scanning head often needs services, such as coolingwater, gas, or RF cables 132. Bending of cables and support members canimpact both reliability and performance. Some serviced reading andwriting heads are heavy, bulky or otherwise unsuitable for fastmovements.

Systems that rely on x-y stage movement typically have heavy stages withlarge inertia that are very stiff to avoid sag and relatively unimpactedby outside vibrations. The heavy scanning stages require forceproportional to their mass to accelerate and stop as they changedirection.

Problems with writing increase as the target surfaces become larger andare made from thinner, more easily deformed materials. Larger stagesrequire increased stiffness. More easily deformed materials requirepattern manipulation from one layer to the next, on a piece by piecebasis.

Accordingly, an opportunity arises to develop a new fast scanningarchitecture with improved throughput. A relatively low cost system withhigh performance may result.

SUMMARY OF THE INVENTION

The technology disclosed relates to scanning of large flat substratesfor reading and writing images. Examples are flat panel displays, PCBsand photovoltaic panels. Reading and writing is to be understood in abroad sense: reading may mean microscopy, inspection, metrology,spectroscopy, interferometry, scatterometry, etc. of a large workpiece,and writing may mean exposing a photoresist, annealing by opticalheating, ablating, or creating any other change to the surface by anoptical beam. The present disclosure provides for a method and apparatusfor writing to (or reading from) a workpiece, including using astationary optical image device, e.g. a modulator (or a detector), toform (or collect) relayed image information and further relaying theimage information along optics of at least one rotating arm between thestationary optical image device and a surface of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art system exposing a flat workpiece with parallelswaths and having a reciprocating scanning action.

FIG. 2 shows an example embodiment where the same workpiece as in FIG. 1is exposed with a rotating action using a stationary writing head androtating scan optics.

FIG. 3 shows an example embodiment with the same orientation of theimage going into and coming out from the scan optics.

FIGS. 4-5 depict stitching together of successive stamps, when thestationary image device is two dimensional. Alternatively, a sweepingaction can be used, instead of a stamping action, to relay informationbetween the stationary image device and the surface of the workpiece.

FIG. 6 shows the same type of scanning action as in FIG. 3, but with theimage rotated 180 degrees.

FIG. 7 shows in the upper row rotated and isotropically magnified imagesthat are compatible with a non-rotating pixel map. In the lower row areexamples of reversed images that are incompatible.

FIGS. 8 a-c show examples with scan optics which give non-rotating pixelmaps.

FIG. 9 shows an example system with a mirror system which can be set toany desired orientation of the image at the exit from the scan optics,having a Dove prism for rotation of the image.

FIGS. 10 a-b show a pair of on-axis writing or reading systems that havea writing or reading device projected at the center of the hub, on itsaxis of rotation.

FIG. 11 depicts a scanning system with three arms and a pair ofworkpieces being written on opposite sides of the hub.

FIGS. 12 a-b show an off-axis embodiment having eight arms and how arotating prism at the hubs image data to and from each arm in turn.

FIGS. 13 a-b compare on- and off-axis relay arms.

FIGS. 14 a-b depict alternative ways to produce an optical axisperpendicular to the workpiece.

FIG. 15 introduces to the optical configuration a tube lens after thepyramid mirror.

FIGS. 16 a-c depict conditions that contribute to maintaining theazimuthal orientation of an image.

FIG. 17 depicts yet another optical configuration that mitigatesrotation of a relayed image by keeping the inboard relay leg parallel tothe axis of rotation.

FIGS. 18-19 illustrate the use of a four sided and three sided pyramidmirror.

FIG. 20 illustrates use of a small size objective lens.

FIG. 21 illustrates a design in which the beam is focused at an entrancepupil and relayed through a telecentric objective lens system.

FIGS. 22 a-b contrast use of a large pyramid mirror with optics thepermit use of a smaller pyramid mirror.

FIG. 23 depicts simplified optics.

FIG. 24 shows another embodiment of the technology disclosed withpossible image generators IG₁₋₈ and an example image detector ID.

DETAILED DESCRIPTION

The following detailed description is made with reference to thefigures. Preferred embodiments are described to illustrate the disclosedtechnology, not to limit its scope, which is defined by the claims.Those of ordinary skill in the art will recognize a variety ofequivalent variations on the description that follows.

This disclosure covers embodiments of a rotating arm printing or viewingdevice with relay optics with a hub at one end of the arm and optics atthe other end, which couple image information with the surface of aworkpiece. The optical coupling at the hub may be either on or off theaxis of rotation.

In certain embodiments, the disclosed technology provides for a methodand apparatus for writing to (or reading from) a workpiece, includingusing a stationary optical image device to form (or collect) relayedimage information and further relaying the image information alongoptics of at least one rotating arm between the stationary optical imagedevice and a surface of the workpiece. By repeatedly sweeping a curvedstripe across the surface of the workpiece, a contiguous image may bewritten from overlapping partial images by stitching together thepartial images on the workpiece.

In another embodiment, the pattern information, e.g. partial images,relayed between the optical image device and the surface of theworkpiece is relayed through with a substantially constant azimuthalorientation. In yet another embodiment, the azimuthal orientation of therelayed image information is substantially constant when a set image atthe optical image device maintains a constant angular relationship torelayed versions of the set image on the workpiece with no more than a0.5 degree rotational variation in the angular relationship when therelayed versions are separated by more than 5 degrees sweep of therotating optical arm.

Maintaining the azimuthal orientation of the image during the sweep ofthe printing arm makes it possible to create a contiguous pixel maprepresenting the surface of the workpiece. In certain aspects of thedisclosed technology, the pixel grid is displaced between consecutivepartial images and the data path of the system must know thedisplacement of each field. Computational operations in the data pathmay then be used to compensate for the displacement of the fields inorder to provide for the stitching of partial images, either beforewriting to or upon reading from the workpiece, e.g. the features in thedata have to be moved to compensate for the displacement.

One aspect of the disclosed technology is that the arm can be placedradially in a rotating disk or rotor and the rotor can have severalarms, e.g. 2, 3, 4, 6, or 8 arms, thereby multiplying the scannedsurface area per time unit. Another aspect is that heavy, complex,fragile machine parts, or parts that are expensive or need manyconnections and services can be placed stationary near the center or hubof the rotor and be shared by the multiple arms. A further aspect of thedisclosed technology is that an image is relayed between an image deviceplaced stationary near the hub of the rotor and the workpiece throughthe radial arm and that the relayed image is essentially non-rotatingwhen the rotor rotates. It is another aspect of the disclosed technologythat partial images are created when the rotor rotates and that thepartial images are stitched together to a continuous curved stripe. Yetanother aspect of the disclosed technology is that the stitchingtogether of partial images is done with bitmaps which are essentiallynon-rotating, but where the pixel grid is displaced from image to image.

This technology is disclosed by reference to relay optics because it canbe used to write to or read from a workpiece. For instance, it is usefulto write directly to a large area mask or a PCB. Or, it can be used toinspect a large area mask. It is used with a workpiece positioningmechanism, such as a stage, details of which are outside the scope ofthis disclosure.

Some particularly useful applications of this technology is for writingpatterns on electronic substrates, such as wafers' front and back sides,PCBs, build-up and interposer substrates, for flexible interconnectionsubstrates and for masks, stencils, templates and other masters.Likewise, the rotor writer can be used for patterning panels indisplays, electronic paper, plastic logic and for photovoltaic cells.The patterning can be done by exposure of photoresist, but also throughother actions of light such as thermal or photochemical processes:melting, evaporation, ablation, thermal fusing, laser-induced patterntransfer, annealing, pyrolytic and photo induced etching and deposition.

The disclosed technology replaces the customary Cartesian flatbed xystage with a polar scanning motion. One of the benefits is one of higherthroughput, economics and mechanical simplicity. The scanning action isdone by a rotating motion which is mechanically easier to build to highaccuracy than straight-line motion. The position accuracy of a point onthe periphery of the rotor is determined by the quality of a bearing andthe accuracy of an angle encoder, both components which can be boughtcommercially with high quality. Another benefit is to reduce vibrationsand transient forces during scanning and between scanning strokes. Awell balanced rotor emits essentially no vibrations or reactive forcesto the supporting structure, while reciprocating straight movements needto reverse their momentum twice per stroke and create strongdisturbances when doing so. The forth benefit is a higher scanningvelocity with less mechanical overhead. With a rotor with several armsonly a small portion of each stroke need to be sacrificed, e.g. a rotorwith four arms may scan through an 80 degree arc and out of the 360degrees in one turn scanning takes place during 4×80=320 degrees. Areciprocating movement will need more mechanical overhead and theoverhead gets larger with increased scanning velocity.

Rotating motion has been used in prior art in drum scanners and drumplotters, with certain advantages in terms of higher scanning velocityand reduced mechanical overhead. But for substrates, especially largesubstrates, which cannot be mounted on a drum rotation has not been useddue, perhaps, to mechanical complexity. The Applicant has found apractical way of letting a stationary image device with a small field bescanned over a large flat workpiece at high speed and to stitch togethera contiguous image.

As mentioned above, systems according to the disclosure can be builtwith very high data rate and throughput and may be used for other typesof patterning where these characteristics are useful: photo-setting,printing, engraving, security marking, etc. The rotor has a smoothmovement and small mechanical overhead even at high rotation speeds,e.g. 60, 120, 300, 600 r.p.m. or higher. The scanning speed, which isthe peripheral speed of the rotor, may be higher than comparablereciprocating systems, e.g. 2, 4, 8, 20 m/s or higher.

An example of a possible system is a rotor one meter in diameter,spinning 3.3 turns per second with a centripetal acceleration of 20 g.The acceleration force gives a constant force on rotating components,such that a lens weighing 50 grams will feel a constant force outwardsof 10 N. With four arms it writes 13 strokes per second with aperipheral velocity of 10 m/s, a mechanical speed which is quiteimpossible with a reciprocating stage. Furthermore, with properbalancing and design of the bearings the motion will be smooth, havehigh mechanical precision and need only little power to be sustained. Ifthe image generator is a micromechanical 1D SLM with 2 MHz frame rateused for creating a 1D partial image on the workpiece, the reloading ofthe SLM would occur every 5 microns along the scanning direction and thepixel size could be 5×5 microns, allowing line width of less than 15microns to be written. With a micromechanical SLM, e.g. a 1D SLM, havingapproximately 8000×1 pixels, each stroke would fill a stripe 40 mm widewith pattern, and cover—with some reduction for the non-straightscan—0.3 square meters per second or 20 square meters per minute. Thisis a very high coverage rate, compared to other writing technologies.

One aspect of the disclosed technology is the introduction of rotatingoptics for printing an essentially non-rotating image on the workpiece.The disclosure also gives the conditions for an exactly non-rotatingimage. In practical cases it may be suitable to deviate slightly formthese conditions, e.g. for reasons of physical space near the hub of therotor. The disclosed technology does still work for small deviations inthe angles, but they have to be corrected for in the data handling. Thiswill be described further on.

Hence, the disclosed technology provides for a rotating scanningarchitecture for fast writing (or reading) of a pattern on a workpiecewith a very high coverage rate compared to other writing (or reading)technologies. As mentioned above, the rotating scanning architecture ofthe disclosed technology may nevertheless allow line widths of less than15 microns to be written. State of the art writing (or reading) systemsthat rely on x-y stage movement typically have heavy stages with largeinertia that often are very stiff in order to avoid sag. These heavystages require a force proportional to their mass to accelerate and stopas they change direction. By introducing a rotating scanningarchitecture with smooth movement and small mechanical overhead even athigh rotation speed, the disclosed technology provides for a solutionwith improved performance that also addresses the above-mentionedproblems associated with the heavy stages and large inertia of state ofthe art x-y stage systems.

The optics relay an image through the rotating arm (s) while maintainingthe azimuthal orientation of the image as the arm scans the workpiece.We define azimuthal orientation with the following example: Consider anarm oriented at noon on a clock face. In this position, the letter “R”has an upright orientation at both ends of the optics, relative to noonon the clock. Then, when the arm is repositioned at 10 or 2 o'clock, theletter “R” would still have the upright orientation at both ends of theoptics. In a writing device, a projected “R” would be printed with thesame upright azimuthal orientation at all three positions, 10, 12 and 2o'clock. Or, in an inspection device, three “R” images positionedupright at the 10, 12 and 2 positions on the workpiece would be viewedas the same. Alternatively, the letter “R” could be inverted, rotated ortransformed by the optics. Still, even after these transformations, theprojected image would have the same azimuthal orientation at all threepositions, 10, 12 and 2 o'clock. Maintaining the azimuthal orientationsimplifies printing. FIG. 4 shows fields 445 that are written or readwhen the rotor with non-rotating optics is rotated (an example with atwo-dimensional fields e.g. from an SLM or CCD camera at the hub 430).The fields in FIG. 4 are taken at intervals which are chosen so that thepixel grid in the horizontal direction is maintained. The pixel grid inthe vertical direction is different for each field with a displacementwhich is given by the curvature of the stripe. FIG. 5 shows a similarexample where the fields are taken without regard of the horizontalgrid, e.g. at equidistant times. The pixel grid is displaced in both xand y between consecutive fields. In order to stitch together acontiguous image the data path of the system must know the displacementof each field.

For a writing system the features in the data have to be moved tocompensate for the displacement and the pixel grid displacement need tobe taken account of while creating the bitmaps for the writing hardware.For a reading system the field may be stitched by known methods used forphotographs, e.g. for stitching together panoramas from multiple images.In either case there is a physical image on the surface, which ishandled by the image device in displaced fields, and in the data path orimage processing computer, i.e. before writing or after reading, itexists as a contiguous image file without reference to the writing orreading hardware, i.e. all parts of the contiguous image have a commonreference grid.

Bitmaps that represent the partial images may be converted between thegrid of the hardware and the reference grid by methods well known in theart of image processing, e.g. algorithms for so called “image morphing”,after the grid of the partial images have been determined from themachine geometry. The signal processing methods devised by the Applicantfor stitching displaced image fields together may also be used withimage fields that are rotated. Small rotations are much easier to handlethan large ones, which have problems with moiré effects, loss ofdefinition, and inefficient use of the sensor area. Therefore it iseasier and the image quality and speed are better with non-rotatingfields, and the second best is a field that rotates only by a fractionof a pixel between adjacent partial images.

Likewise the technology disclosed enables many instruments to be used onlarge flat substrates and scanning at high speed, e.g. on solar panels,display substrates, sheet metal, architectural glass, roll-to-rollplastic, paper, and the like. Through the rotating arms an image may becaptured at the periphery and transferred to the hub where a camera ordetector (e.g., a vidicon, CCD, CID, CMOS device, and/or a TDI,intensified, gated, avalanche, single photon, photon-counting,interferometric, colorimetric, heterodyne, photoconductive or bolometricdetector or array) is located, or an optical analytical instrument maybe situated, (e.g., a reflectometer, spectrophotometer, colorimeter,scatterometer, multispectral camera, polarimeter, or a fluorescence,photo-luminescence or photoacoustic instrument).

Other possible uses are for optical measurements of heat (infraredemission), color, flatness, smoothness, film thickness, chemicalcomposition, cleanliness, or for verification of pattern integrity orfidelity. The method is particularly beneficial where an image of thesurface or an exact location of a found defect or feature is needed.Instruments that are complex, bulky or fragile can be mounted fixed atthe hub and still access any point on the surface of, say, a two meterwide thin-film photovoltaic panel passing on a conveyor under the rotor,thereby enabling full-area inspection or analysis at dense grids onlarge workpieces without removing sheets for analysis or stopping theroll-to-roll flow. The rotor may have only flat optics or it may havereflecting relays in the arms, allowing achromatic use from far IR todeep UV. The illumination (e.g. visible incident light forreflected-light microscopy or UV for fluorescence studies,) may bebrought from the hub or it may be generated within the rotor. Severalinstruments and or writing modes may be combined in one rotor, either bybeing combined in one optical arm or by employing different ones. Therotation may be continuous with a constant or varying angular speed oralternatively be driven by in a stop and go fashion, in particular forrandom-access analysis of workpieces. Focusing of the imaging optics maybe fixed, variable from time to time or dynamic during scanning andbased on feedback from focus sensors based on interferometry,back-reflection, proximity to a fiber end, optical triangulation,optical defocus or parallax; fluid flow, pressure or viscous resistance;ultrasound time-of-flight or phase; capacitance, inductance or othersuitable phenomena indicating a distance or position.

With the image orientation preserved by the rotating optical arm,computation of overlapping images is enabled or simplified, even thoughthe overlap between stamps changes with the angle course of rotation, asillustrated by FIG. 5. One image “stamp”, for instance produced by aflash of radiation, can be related to another by a simple displacementvector, without worrying about rotation or skewing of the image. Asecond displacement vector can account for movement of the workpiecebetween flashes, if it is in motion. The two displacement vectors can beadded.

The more detailed disclosures that follow depict two families of opticalarrangements. The first family uses an optical relay on the axis ofrotation. In two embodiments, flat and curved mirrors are placedon-axis. In variations, one or more arms can be used for relayinginformation between a hub and a distal arm end that sweeps theworkpiece. The second family uses an optical relay near the hub, whichis off-axis. Examples of off-axis relays include triangular, squarepyramid and mirrors such as multifaceted mirrors.

In certain embodiments of the disclosed technology, the optical relay isan image-deflecting device, such as a prism or mirror, which may beplaced on or off-axis and is rotating about the axis of rotation. Theimage-deflecting device may e.g. be a separate element having its ownmovement, e.g. a rotational movement, which at least during certainperiods of time is synchronized with the rotational movement of the axisof rotation of the hub or the image-deflecting device may also be anintegral part of the rotating hub.

Substantial scanning speeds can be achieved using one or more rotatingoptical relay arms. The motion of the workpiece need not be reversed asmany times with rotating optics as with scanning optics, because a widerstripe of the workpiece can be scanned. Alternatively, much lessexpensive optics can be used to accomplish a wide scan field.

FIGS. 2, 4 and 5 show exemplary embodiments of scanning through an arc,instead of using a straight motion. In all of the figures, the opticsare greatly simplified to improve comprehension of the mechanicalrelationships among components and to focus the reader on the rotatingarms. The reading/writing head 230 is stationary. The optical image isrelayed by a rotating or swinging optical system 240 between a positionnear the axis of rotation and a position away from the hub 250. Therotating optical system may be simple and light, e.g. consisting only oftwo parallel mirrors. It scans a circular arch over the workpiece (FIGS.4-5) or swings (FIG. 2). The workpiece 410 is moveable, at leastrelative to the center of rotation of the optics. The workpiece may bemoved either continuously or in steps, so that the scanning optics canreach all parts of the workpiece. A control system knows from theactuators driving the motions or from position and/or angle encoderswhich part of the workpiece is being written to/read from. For writing,the controller controls the sending of the data intended to be writtento the addressed area, and for reading the read image or data isrecorded or analyzed with awareness of where it came from. Maintainingthe azimuthal orientation of the image 430, 445 during the sweep of theprinting arm makes it possible to create a contiguous pixel maprepresenting the surface of the workpiece, either before writing to orupon reading from the workpiece. Note that the overlap between stampsdepends on the position of the distal arm, e.g., 545A-D, in the arc ofrotation.

Circular motion is easier to control than a linear one. Bearings, e.g.fluid bearings, define the center of rotation accurately. If therotating part is made as a wheel with balancing masses around the centerof rotation and given a continuous rotational moment, the only energyneeded to sweep the scanning arms compensates for the friction in thebearing. A rotor, including rotating optics and a mechanical support,may be completely passive. All active parts such as motors, cooling,sensors etc. may be part of the base and stage.

The technology disclosed replaces the reciprocating motion of an x-yscanning system with a continuous rotation of optical arms. Thisrotation exchanges no energy and little or no vibration with theenvironment. By comparison, reciprocating motion at 1 m/s causesvibrations and reciprocating mechanical forces in the supportingstructure, while a rotating balanced scanner may go 10 m/s verysmoothly. Replacing reciprocating motion with circular motion solvespractical problems in optical scanning systems, in particular for flatworkpieces.

Maintaining the azimuthal orientation of an image is illustrated in FIG.3. The azimuthal image at the hub 330 is relayed to the end of rotatingarm 240A, 240B. The distal image 345A, 345B has the same azimuthalorientation as the hub image 330. In the illustrated embodiment, therelay axes 334, 344 are parallel and transmitting image information inthe same direction.

FIGS. 16 a-c depict and define the optical parity of the relayed image.The light is propagating through a rotating optical system indicated bythe mirrors M1 and M2. Mirror M1 is at or near the axis of rotation.Mirror M2 is at the distal end of an optical arm that rotates about ahub. Mirror M2′ (prime) represents mirror M2 in a rotated position. Thelight beam contains information about an image with an x and a ydirection. The x and y directions, as they enter the rotating opticalcomponent, combine with a propagation direction z to form a threedimensional coordinate system with a certain handedness, shown asright-handedness (“RH”) in the figure. The rotating optics may transformthe image information before the light hits the workpiece. The x and ydirections of the image information may be transformed, but they willretain some right- or left-handedness relative to the direction ofpropagation. A condition for the image to be non-rotating is that thehandedness is the same before and after the rotating parts, if thedirections of entry into and exit from the rotating optics are paralleland the handedness is opposite if the directions are anti-parallel. Thisis shown in the figures. In FIG. 16 a, the handedness before mirror M1is the same as the handedness after mirror M2. The entry and exit areparallel, both initially and when the mirrors are rotated 90 degrees toa new position (indicated by dashes) from the original position (solid)the x and y axes have not rotated. In FIG. 16 b, mirror M2 is mounteddifferently so that the z axis is reversed. The xyz system is stillright-handed, but the directions of propagation before and after therotating parts are anti-parallel. In this case, it is seen that when themirrors rotate through 90 degrees the x and y axes in the outgoing lightbeam are rotated by 180 degrees. In other word, the azimuthalrelationship between the image information entering and exiting therotating optics is not maintained when the handedness violates the rulesgiven above. Finally, in FIG. 16 c, a third mirror M3 is introduced toreverse the handedness of the xyz coordinate system, making xyzleft-handed LH. The reverse handedness combined with the anti-parallelentry and exit to the rotating optics results in x and y orientationthat are non-rotating.

A different way of expressing the condition is to form a xyr coordinatesystem before and after the rotating parts, where r is the rotationvector i.e. it is parallel to the axis of rotation and the rotation isclockwise when looking along r. The condition for a non-rotating imageis that the handedness of xyr is the same before and after the rotatingparts. This last way of formulating the condition together with therestriction that the magnitude of r (i.e. speed or angle of rotation) isalso the same allows the condition for non-rotating image to begeneralized to more complex geometries.

FIGS. 4-5 depict stitching together of successive stamps, when thestationary image device is two dimensional. Alternatively, a sweepingaction can be used, instead of a stamping action, to relay imageinformation between the stationary image device and the surface of theworkpiece. In a sweeping action, the image device may be one-dimensionalor may be an array of beams and may more or less continuously relayimage information as it sweeps along an arc. In FIG. 4, the stationaryimage device 430 is at the center of a circle described by one or moreoptical arms that rotate about a hub. In this figure, the rotation isclockwise. Stamps 445 map to the surface of the workpiece 410.Typically, stamps from writing are produced by a pulsed laser and SLM,DMD, GLV, liquid crystal shutter system or similar device for creatingan image. Stamps for reading, as used in inspection or metrology, forinstance, relay information in the reverse direction. FIG. 5 shows howthe overlap or so-called stitching between successive stamps 545A-Ddepends on the position of the optical arm relative to the workpiece410.

FIG. 6 shows the same type of scanning action as in FIG. 3, but with theimage rotated 180 degrees. Rotation and isotropic magnification ordemagnification are optical operations that preserve the so-calledparity of the image. In a system with parallel axes at the hub anddistal end, the parity of the image is the same going into and comingout of the scan optics when the image is reversed an even number oftimes (0, 2, 4 . . . ). Maintaining the parity of the image simplifiesfusion of partial images. A system with anti-parallel axes is a specialcase, which we discuss in connection with FIG. 8 c, below.

FIG. 7 shows in the upper row rotated and isotropically magnified imagesthat are compatible with a non-rotating pixel map. In the lower row areexamples of reversed images that are incompatible with straightforwardfusion of successive images.

FIGS. 8 a-c show examples with scan optics that give non-rotating pixelmaps. FIG. 8 a illustrates a writing (or reading) system with twoparallel mirrors 852, 854 and image forming optics before the mirrors861. The axes 857, 857 at and away from the hub are parallel. FIG. 8 billustrates a reading (or writing) system with two parallel mirrors witha symmetrical optical system 862, 863 in the scan arm. FIG. 8 c shows asystem where the light beam is directed above the axis of the scan armand hits an optical component 864 such as a stationary external mirror.The optical component 864 addresses the case of anti-parallel imagepaths at and away from the hub.

FIG. 9 shows an example system with a mirror system that can be set toany desired rotation of the image 855, 859 between entrance to and exitfrom the scan optics. A Dove prism 965 is one optical component suitablefor rotation of the image. If the Dove prism is set to a fixed angle theimage will be non-rotating, but turned by twice the angle of the Doveprism. Rotating the Dove prism while rotating the arm may be a way ofcontrolling the rotation of the image with high precision, e.g. forcancelling a residual rotation due to non-perfect angles.

FIGS. 10 a-b show a pair of on-axis writing or reading system that havea writing or reading device projected at the center of the hub, on itsaxis of rotation. The writing or reading device 1030 may be anyimage-forming device, e.g. an SLM or display, or an image-collectiondevice such as a camera or other detector. Both systems use acatadioptric system for scanning the image on a radius. The rotatingportion of the scan optics is the part inside the dashed rectangle 1040.The system uses an Offner projection system with small 1045 and large1043 stationary mirrors. Image data 1050 directed for or from theworkpiece is reflected off the stationary mirrors 1043, 1045 onto aseries of rotating mirrors, including at least one on-axis mirror 1041,from or to the writing or reading device 1030. The workpiece 1010 iscarried on a stage 1020.

FIG. 10 b shows a similar system where a large stationary mirror 1043 isreplaced by a smaller curved section of a mirror 1044. In thisconfiguration, the size of the sectional mirror 1044 can be reduced bysetting the curved mirrors 1044, 1045 in motion, or at least setting thereduced size sectional mirror 1044 in motion.

Systems with three, four or more arms are contemplated to increase theduty cycle of the system, so that writing or reading occupies a greaterproportion of each rotation of optics. FIG. 11 depicts a scanning systemwith three arms and a pair of workpieces 1111, 1112 being written onopposite sides of the hub 1148. This system may have a duty cycle of100%. Each rotor writes through an arc of 60 degrees. Only one arm 1140writes at a time, alternatively on the two workpieces 1111 and 1112. Thelaser energy is switched by polarization control 1132 between the twoSLMs 1147 and 1149, and the data stream is also switched between theSLMs. Since the laser 1120 and the data path 1135 are among the mostexpensive modules in a writing machines, this embodiment has beendesigned to use laser and data channel 100% of the time while the SLMsand the optics in the arms has lower duty cycles, 50% and 33%respectively. This may be, for instance, an example of a writing systemwith three rotating arms 1140A-C. Each of the arms may correspond indesign to any of FIGS. 3, 5, 8 a-c or 9. The figure conceptually depictsa laser 1120 and a controller 1135 sending data to two SLMs 1130 whichare relayed 1132, 1147, 1149 to the rotating arms. It shows how each armmoves in front of each SLM and writes a series of concentric stamps onthe workpieces 1111, 1112. While two workpieces are shown in thisfigure, more workpieces could be positioned under a rotor, depending onits size. While the example is described as a writing system, thedirection of relay could just as easily be from the workpiece back to apair of detectors positioned where the laser 1120 is and elsewhere.

FIGS. 12 a-b show an off-axis embodiment having eight arms and how arotating prism at the hubs image data to and from each arm in turn. FIG.12 a is a side view that reveals the workpiece 1210 and stage 1220. Thelaser 1230 (or detector) relays data over an off-axis mirror or otheroptical element 1242 to a rotating mirror or prism 1271. A pair ofmirrors or prisms 1248, 1249 rotate with the arms. Using pyramidaloptics, one side of the optical element 1248, 1249 pushes image databetween the prism 1271 to the large stationary mirror 1243 and the otherside pushes image data between the large stationary mirror 1243, adistal mirror 1247 and the workpiece 1210.

FIG. 12 b is a top view of the system described immediately above. Thelarge stationary mirror 1243 is shown and cut away to reveal underlyingfeatures. The small stationary mirror 1245 is also shown and cut away toreveal the rotating prism 1271. The small stationary mirror has beenslightly offset in the drawing, instead of centered as it would be inthe device, to make the rotating mirror 1271 more apparent.

Additional drawings further explain off-axis geometries. FIGS. 13 a-bcompare on- and off-axis relay arms. The side views clearly contrast therelay at the hub, between the on-axis arrangement of FIG. 13 a and theoff-axis arrangement of FIG. 13 b. The side view more clearlyillustrates this compared with the top view. A pair of top viewscontrasts a simple rotating mirror 1370 and a multi-faceted off-axisprism or mirror 1371. As an arm rotates from zero to 45 degrees in anon-axis system, the optical relay is essentially invariant. An off-axissystem is different, as the distance from the axis to the exact relaypoint on the multi-faceted element 1371 changes. The part of themulti-faceted element 1371 that forms the relay shifts from one side ofthe arm's center line 1341 to the other. In some embodiments, thisrequires a larger optical element 1362 positioned distal to the hub thanrequired for an on-axis system, which keeps the relay on the arm'scenter line 1341.

FIGS. 14 a-b depict alternative ways to produce an optical axisperpendicular to the workpiece 1430, using a non-parallel axis at thehub 1412, which is tilted relative to the axis of rotation 1410. Theseembodiments bring the optical relay to the center of a distal lens 1426in both the base and rotated cases. In FIG. 14 a, the interior anglesare equal between the relay 1424 and the axes at the hub and onto theworkpiece 1430. To match these angles, the relay 1424 between the huboptics 1420 and the distal optics 1428A is out of the planeperpendicular to the axis of rotation 1410. In FIG. 14 b, the angle ofthe hub optics 1422B is adjusted from 1422A, to keep the relay 1424between the hub optics 1420 and the distal optics 1428A in the planeperpendicular to the axis of rotation 1410. The adjusted angle of thehub optics facet produces unequal interior angles between the relay 1424and the respective axes at the hub and onto the workpiece 1430. Theangle at the distal optical element 1428B is a right angle, between theplane perpendicular to the axis of rotation and perpendicular to theworkpiece.

Using a tilted angle of incidence at the hub, so that that relay leg isnot parallel to the axis of rotation, produces a certain image rotation.In most cases, this image rotation is small, less than 0.5° over a rangeof pyramid rotation angles of 0-45°. Alternatively, the image rotationmay be less than 0.5° over a range of pyramid rotation angles of 0-5°.

FIG. 15 introduces to the optical configuration a tube lens after thepyramid mirror. The tube lens objective is arranged so that the systemis telecentric. Somewhat oversized lenses are required to accommodatethe pyramid mirror. In various implementations, the beam incident to thepyramid mirror may be parallel to the axis of rotation or tilted.

FIG. 17 depicts yet another optical configuration that mitigatesrotation of a relayed image by keeping the inboard relay leg 1712parallel to the axis of rotation 1710. The lens section 1715 is notsymmetrical with respect to the axis of the relay leg 1712, so the relayleg after the lands 1717 is bent toward the surface 1722 of the pyramidmirror 1720. The relay along the arm 1724 is perpendicular to the axisof rotation.

FIGS. 18-19 illustrate the use of a four sided and three sided pyramidmirror, respectively. Both of these implementations are off-axis. Largernumbers of sides can be used on the pyramid mirror. The practicaltrade-off is between lost projection time, when the beam is straddlingtwo facets of the rotating mirror, which is unfavorable, and a reducedin radius between the center and edges of a facet, which favorablyimpacts the relay of image information along the optical arm, keeping itcloser to the center line of the arm.

FIG. 20 illustrates use of a small size objective lens 2026. The rotorscanner is designed so that the beam is aimed near the front surface ofthe objective lens, which reduces the size of the objective lens. Thesmall lens, on the other hand, is not strong enough to bring the relayleg 2024 coincident to the centerline of the arm 2041. As result, thefocused beam will not be perpendicular to the workpiece.

FIG. 21 illustrates a design in which the beam is focused at an entrancepupil 2125 and relayed through a telecentric objective lens system.However, this requires a larger objective lens and a more complexoptical design.

FIGS. 22 a-b contrast use of a large pyramid mirror with optics thepermit use of a smaller pyramid mirror. Use of relay optics 2222 beforethe entrance pupil 2225 enables use of the smaller mirror.

FIG. 23 depicts simplified optics that relay the image information froman SLM or detector 2381 through a focus actuator 2383 and onto thepyramid mirror 2320. The focus actuator also may steer the beam tocompensate for errors in the pyramid facets or caused by vibrations.This implementation illustrates use of four arms with one workpiece andone SLM. Features of this implementation can be combined with otherimplementations that use multiple writing or reading devices andmultiple workpieces.

It is contemplated that multiple writing or detecting devices can beused along the same arm and path. In addition, multiple writing ordetecting devices can be positioned around the axis of rotation to writeto multiple workpieces or to a large workpiece.

Likewise the technology disclosed enables many instruments to be used onlarge flat substrates and scanning at high speed, e.g. on solar panels,display substrates, sheet metal, architectural glass, roll-to-rollplastic, paper, and the like. Through the rotating arms an image may becaptured at the periphery and transferred to the hub where a camera oran optical analytical instrument may be situated, e.g. a reflectometer,spectrophotometer, scatterometer, multispectral camera, polarimeter,fluorescence or photo-luminescence instrument. Instruments that arecomplex, bulky or fragile can be mounted fixed at the hub and stillaccess any point on the surface of, say, a two meter wide thin-filmphotovoltaic panel passing on a conveyor under the rotor, therebyenabling full-area inspection or analysis at dense grids on largeworkpieces without removing sheets for analysis or stopping theroll-to-roll flow. The rotor may have only flat optics or it may havereflecting relays in the arms, allowing achromatic use from far IR todeep UV. The illumination, e.g. UV for fluorescence studies, may bebrought from the hub or it may be generated within the rotor.

FIG. 24 shows another embodiment of the technology disclosed withpossible image generators IG₁₋₈ and an example image detector ID. Theimage generator is positioned on a fixed frame and the mirrors M₁ and M₂mounted on the rotor R send the image to the periphery of the rotorwhere it scans over the workpiece WP. The lenses L₁ and L₂ form a relaywhich makes a sharp image of the image I created by the image generatorIG. The rotor drive RD makes the rotor spin and the angle is measured bythe position detector PD₁. The position of the stage is measured by asecond position detector PD₂. The controller C controls the imagegenerator, so that the pattern P is formed correctly on the workpiece.

The image generator can be of many types as shown by the examples IG₁₋₈:IG₁ is a narrow one-dimensional array of light modulators, e.g. agrating light valve. IG₂ is a broad array of modulators which forms anarrow line on the workpiece by anamorphic optics. That is, the ratiobetween the illuminated area on the modulator and on the workpiece isdifferent in x and y. The aspect ratio (length over width) of themodulator is at least two times smaller than the same ratio in theimage, preferably five times smaller, and often will be ten timessmaller. IG₃ is a two-dimensional array of modulators, such as amicromechanical modulator array or a 2D array of LCD shutters. IG₄ is aspot grid array, e.g. formed by a lens array where each lens forms afocus spot and the light in focus spots are individually modulated. e.g.by an LCD shutter or a DMD chip (Texas Instruments' DLP technology). Thearray of spots can also be formed by an array of sources, e.g. VCSELlasers. In IG₅ an irregular array of focus spots is created, e.g. by acomputer-controlled hologram or an SLM. The irregular array can forexample be used to drill vias in wafers, PCBs and other substrates. IG₆has a scanning beam as image generator, e.g. a single-mode laser beammodulated by an acoustooptic or electrooptic modulator and scanned by anacoustooptic, electrooptic, or mechanical scanner. IG₇ has multiplebeams being modulated simultaneously and scanned in parallel. If thepattern is repeated or stereotype, e.g. a line pattern parallel to theworkpiece it may be sufficient to use a mask or stencil as imagegenerator as shown in IG₈. Finally, the optics can be reversed and theimage generator replaced with an image detector, ID shown heresymbolically as a camera. The illumination source may have propertiesadapted to each of the cases above: IG₁₋₂, IG₄₋₇ may use a continuouslight sources or a light source with a high frequency of short pulses,while IG₃₋₅ and IG₈ may be used with pulsed light. The camera IDrepresenting image detectors, spectrophotometers, time-resolvedphotometers, scatterometers, etc. may be used with continuous or pulsedlight depending on the exact need.

As mentioned above, the disclosed technology enables many instruments tobe used on large flat substrates and scanning at high speed, e.g. onsolar panels, display substrates, sheet metal, architectural glass,roll-to-roll plastic, paper, and the like. Through the rotating arms animage may be captured at the periphery and transferred to the hub wherea camera or detector (e.g., a vidicon, CCD, CID, CMOS device, and/or aTDI, intensified, gated, avalanche, single photon, photon-counting,interferometric, colorimetric, heterdyne, photoconductive or bolometricdetector or array) is located, or an optical analytical instrument maybe situated, (e.g., a reflectometer, spectrophotometer, colorimeter,scatterometer, multispectral camera, polarimeter, or a fluorescence,photo-luminescence or photoacoustic instrument).

Other possible uses are for optical measurements of heat (infraredemission), color, flatness, smoothness, film thickness, chemicalcomposition, cleanliness, or for verification of pattern integrity orfidelity. The method is particularly beneficial where an image of thesurface or an exact location of a found defect or feature is needed.Instruments that are complex, bulky or fragile can be mounted fixed atthe hub and still access any point on the surface of, say, a two meterwide thin-film photovoltaic panel passing on a conveyor under the rotor,thereby enabling full-area inspection or analysis at dense grids onlarge workpieces without removing sheets for analysis or stopping theroll-to-roll flow. The rotor may have only flat optics or it may havereflecting relays in the arms, allowing achromatic use from far IR todeep UV. The illumination (e.g. visible incident light forreflected-light microscopy) may be brought from the hub or it may begenerated within the rotor. Several instruments and or writing modes maybe combined in one rotor, either by being combined in one optical arm orby employing different ones. At least one instrument or optical imagedevice may emit an exciting beam through an arm and receives an imageback from the workpiece, e.g. UV for fluorescence studies. The rotationmay be continuous with a constant or varying angular speed oralternatively be driven by in a stop and go fashion, in particular forrandom-access analysis of workpieces. Focusing of the imaging optics maybe fixed, variable from time to time or dynamic during scanning andbased on feedback from focus sensors based on interferometry,back-reflection, proximity to a fiber end, optical triangulation,optical defocus or parallax; fluid flow, pressure or viscous resistance;ultrasound time-of-flight or phase; capacitance, inductance or othersuitable phenomena indicating a distance or position.

Some Particular Embodiments

The disclosed technology may be practiced as a method or device adaptedto practice the method. The disclosed technology may be an article ofmanufacture such as media impressed with program instructions to carryout the computer-assisted method or program instructions that can becombined with hardware to produce a computer-assisted device.

In this section, we will describe methods and devices both in terms of apath that may convey image information in either direction and in termsof an image device that may be a transmitter or receiver of imageinformation to or from a workpiece. One of the disclosed methods is amethod of scanning a workpiece 1111. This method can apply either towriting to or reading from the workpiece. The method involves using atleast one optical arm 1140A-C rotating about a hub 1148 to relayinformation between an optical image device 330, 1130 and a workpiece310, 1111. The optical image device may be a writing device, such as anSLM or DMD, or a reading device, such as a CMOS detector array. It maybe 2D or 1D and swept. The workpiece is positioned to be generallyperpendicular to an axis of rotation of the optical arm. The relayedimage information maintains a substantially constant azimuthalorientation between the image device and the workpiece. In this method,the relay follows a path that extends from the workpiece 310, 1111, allalong the optical arm 1140A-C, over a hub 1148 and to the image device1130. The relayed image information may be conveyed either directionalong this path. The azimuthal orientation of the relayed information isdefined to be substantially constant between the image device 330 andthe workpiece 310 when a set image at the optical image device 330, 630maintains a constant angular relationship to a relayed version 345A-B,645A-B of the set image on the workpiece 310. The angular relationshipis considered substantially constant when it varies by no more than onehalf of the degree in rotation as the optical arm sweeps through 5° ofrotation 347. In some implementations, the angular relationship willvary by no more than one half of the degree in rotation as the opticalarm sweeps through 45° of rotation 347. An upright “R” on the workpieceshould be upright regardless of whether the optical arm 240A-B is at 10o'clock, noon or two o'clock in its rotational sweep 347.

In one implementation, the optical image device 330, 1130 used in thismethod forms an image that is relayed to the workpiece 310, 1111. Thatis, it writes to the workpiece. This relayed image information may beconveyed in a pulsed series of stamps. Or, it may be conveyed as a sweptarray of writing beams.

In another implementation, the optical image device 330, 1130 used inthis method detects an image that is relayed from the workpiece 310,1111. That is, it reads the workpiece.

This method further may include reading from or writing to the workpieceand assembling composite image information 545A-D corresponding to animage at the workpiece spanning some part of the optical arm's sweep.For instance, the composite image information may correspond to at leastfive, ten or twenty degrees of sweep. The composite image informationmay be information read from the workpiece or it may be a map ofinformation to be written to the workpiece or to be resampled andwritten to the workpiece.

Of course, the embodiments, implementations, aspects and features of thefirst method above can be combined in numerous ways to produce a varietyof systems.

A second method embodiment is a method of writing to or reading from aworkpiece 1010. A stationary optical image device is used to form orcollect relayed image 1050 information (FIGS. 4, 10 and 11). The methodinvolves using at least one rotating arm 1140A-C that relays 1424information between an optical image device 330, 1130 and a workpiece310, 1111. The optical image device may be a writing device, such as anSLM or DMD, or a reading device, such as a CMOS detector array. It maybe 2D or 1D and swept. A curved stripe is repeatedly swept across thesurface of the workpiece to write or read a contiguous image 430 formedfrom overlapping images that are stitched together. Optimally,maintaining the azimuthal orientation of the image 430, 445 during thesweep of the printing arm simply for creating a contiguous pixel maprepresenting the surface of the workpiece, either before writing to orupon reading from the workpiece.

The angular relationship is considered substantially constant when itvaries by no more than one half of the degree in rotation as the opticalarm sweeps through 5° of rotation 347. In some implementations, theangular relationship will vary by no more than one half of the degree inrotation as the optical arm sweeps through 45° of rotation 347. Anupright “R” on the workpiece should be upright regardless of whether theoptical arm 240A-B is at 10 o'clock, noon or two o'clock in itsrotational sweep 347.

In yet another implementation, the relaying of image 430 informationincludes traversing a first optical axis coupled to the stationaryoptical image device and positioned at or near an axis of rotation 1310of the rotating arm 1724. A second optical axis is traversed, which hasbeen attached to the surface 1722 and positioned distally along therotating arm from the axis of rotation. The first and second opticalaxes are substantially parallel or anti-parallel 859 to each otherwithin about eight degrees 1412.

In another implementation, the second optical axis can be at least tentimes as far from the axis of rotation 1310 as the first optical axis.

In another implementation, the optical parity (FIGS. 16 a-c) of therelayed image 1050 information is preserved when the first and secondoptical axes 857 are substantially parallel and reversed when they aresubstantially anti-parallel 859.

In a first device embodiment, an optical scanning device is described.This device may be either a writing or reading device 1030. The deviceinvolves using at least one optical arm 1140A-C rotating about a hub1148 having an axis of rotation. The device has a hub, which may includeon-axis (FIG. 10) or off-axis (FIGS. 11-15) relay of information betweenan optical image device 330, 1130 and a workpiece 310, 1111. Theworkpiece is positioned to be generally perpendicular to an axis ofrotation of the optical arm on a stage that is part of the device. Thedevice includes an image device 330, 1130. The relay optics relayoptical information between the image device 330, 1130 and the workpiece310, 1111 while maintaining a substantially constant azimuthalorientation between images at the image device 330, 630 and the relayedversion 345A-B, 645A-B. In this device, the relay follows a path thatextends from the workpiece 310, 1111, along the optical arm 1140A-C,over a hub 1148 and to the image device 1130. The relayed image 1050information may be conveyed either direction along this path 1312. Animage processor 1135 assembles a contiguous image 430 corresponding tothe relayed image 1050 information using a rotating arm 1724 sweepingover parts of the surface 1722. When the device is a writing device, theimage processor 1135 writes parts of the contiguous image onto thesurface to form a contiguous curved stripe. When the device is a readingdevice, the image processor reads parts of the contiguous image from acontiguous curved stripe on the surface and stitches the parts togetherin memory to form the contiguous image. The azimuthal orientation of therelayed information is defined to be substantially constant when itvaries by no more than one half of the degree in rotation as the opticalarm sweeps through 5° of rotation 347. In some implementations, theangular relationship will vary by no more than one half of the degree inrotation as the optical arm 1140A sweeps through 45° of rotation 347. Anupright “R” on the workpiece 1010 should be upright regardless ofwhether the optical arm 1140A is at 10 o'clock, noon or two o'clock inits rotational sweep 347.

In one implementation, the device can also include a first optical axisof the relay optics 2222 attached to the stationary optical image deviceand positioned at or near an axis of rotation 1310 of the rotating arm1724. The second optical axis of the relay optics 2222 is attached tothe surface 1722 and positioned distally along the rotating arm 1724from the axis of rotation 1310.

In another implementation, the second optical axis can be at least tentimes as far from the axis of rotation 1310 as the first optical axis.

In another implementation, the optical parity of the relayed image 1050information is preserved when the first and second optical axes 857 aresubstantially parallel and reversed when they are substantiallyanti-parallel 859.

In yet another implementation, the optical image device forms an image430 that is relayed 1132 to the workpiece 1010.

In alternate embodiments, the part of the path 1312 near the axis ofrotation 1310 for the arm 1724 may be on-axis (FIG. 10) or off-axis(FIGS. 11-15.) These embodiments can be combined in any variety with theimplementations above and other features described below. In someembodiments (FIGS. 8 a-c, 10, 16 a-c), a first part of the path near thehub coincides with the axis of rotation 857, 859. In these so-calledon-axis embodiments, a second part of the path touching the workpiecemay run either parallel 857 or anti-parallel 859 to the part of the paththat is coincident with the axis of rotation. For on-axis embodiments, awide variety of mirror arrangements can be used. For instance, a mirroror prism 854, FIG. 16 M1 can be positioned above the rotating armassembly and can relay information directly onto the rotating arm. Or, amirror or prism 1042 can be positioned below the rotating arm assembly1040 and use overhead mirrors 1043, 1045 in a so-called Offnerprojection system. The Offner projection system brings the relayed image1050 back towards the workpiece 1010, either directly or withredirection along a rotating optical arm. In some implementations, alarge stationary overhead mirror 1043 can be replaced with smallsections of mirrors that rotate 1044 with the arm(s) to maintain theproper position in the optical path. Other on-axis mirror arrangementscould be devised; this list is not intended to be exhaustive.

So-called off-axis embodiments (FIGS. 11-15) have a part of the path1312, 1412 that is near the hub, which does not coincide with the axisof rotation 1310, 1410. In these embodiments, a first part of the path1312 near the axis of rotation 1310 is parallel to the axis of rotationor at least within eight degrees 1412 of parallel to the axis ofrotation 1410. A second part of the path 1330 that touches the workpieceis within eight degrees of parallel to the axis of rotation.Alternatively, the first and second parts of the path may be withineight degrees of parallel to one another.

This method further may include reading from or writing to the workpieceand assembling composite image information 545A-D corresponding to animage at the workpiece spanning some part of the optical arm's sweep.For instance, the composite image information may correspond to at leastfive, ten or twenty degrees of sweep. The composite image informationmay be information read from the workpiece or it may be a map ofinformation to be written to the workpiece or to be resampled andwritten to the workpiece.

Of course, the embodiments, implementations, aspects and features of thefirst method above can be combined in numerous ways to produce a varietyof systems.

A second device embodiment relays optical information onto or from aworkpiece. This device may be either a writing or reading device. Thedevice involves using at least one optical arm 1140A-C rotating about ahub 1148 having an axis of rotation. The device has a hub, which mayinclude on-axis (FIG. 10) or off-axis (FIGS. 11-15) relay of informationbetween an optical image device 330, 1130 and a workpiece 310, 1111. Theworkpiece is positioned to be generally perpendicular to an axis ofrotation of the optical arm on a stage that is part of the device. Thedevice includes an image device 330, 1130. The relay optics relayoptical information between the image device 330, 1130 and the workpiece310, 1111 while maintaining a substantially constant azimuthalorientation between images at the image device 330, 630 and the relayedversion 345A-B, 645A-B. In this device, the relay follows a path thatextends from the workpiece 310, 1111, along the optical arm 1140A-C,over a hub 1148 and to the image device 1130. The relayed imageinformation may be conveyed either direction along this path. Theazimuthal orientation of the relayed information is defined to besubstantially constant when it varies by no more than one half of thedegree in rotation as the optical arm sweeps through 5° of rotation 347.In some implementations, the angular relationship will vary by no morethan one half of the degree in rotation as the optical arm sweepsthrough 45° of rotation 347. An upright “R” on the workpiece should beupright regardless of whether the optical arm is at 10 o'clock, noon ortwo o'clock in its rotational sweep.

In one implementation, the optical image device 330, 1130 forms an imagethat is relayed to the workpiece 310, 1111. That is, it writes to theworkpiece. This relayed image information may be conveyed in a pulsedseries of stamps. Or, it may be conveyed as a swept array of writingbeams.

In another implementation, the optical image device 330, 1130 detects animage that is relayed from the workpiece 310, 1111. That is, it readsthe workpiece.

In alternate embodiments, the part of the path near the axis of rotationfor the arm may be on-axis (FIG. 10) or off-axis (FIGS. 11-15.) Theseembodiments can be combined in any variety with the implementationsabove and other features described below. In some embodiments (FIGS. 8a-c, 10, 16 a-c), a first part of the path near the hub coincides withthe axis of rotation 857, 859. In these so-called on-axis embodiments, asecond part of the path touching the workpiece may run either parallel859 or anti-parallel 859 to the part of the path that is coincident withthe axis of rotation. For on-axis embodiments, a wide variety of mirrorarrangements can be used. For instance, a mirror or prism 854, FIG. 16M1 can be positioned above the rotating arm assembly and can relayinformation directly onto the rotating arm. Or, a mirror or prism 1042can be positioned below the rotating arm assembly 1040 and use overheadmirrors 1043, 1045 in a so-called Offner projection system. The Offnerprojection system brings the relayed image 1050 back towards theworkpiece 1010, either directly or with redirection along a optical arm.In some implementations, a large stationary overhead mirror 1043 can bereplaced with small sections of mirrors 1044 that rotate with the arm(s)to maintain the proper position in the optical path. Other on-axismirror arrangements could be devised; this list is not intended to beexhaustive.

So-called off-axis embodiments (FIGS. 11-15) have a part of the path1312 that is near the hub, which does not coincide with the axis ofrotation 1310, 1410. In these embodiments, a first part of the path 1312near the axis of rotation 1310 is parallel to the axis of rotation 1310or at least within eight degrees of parallel to the rotation. A secondpart of the path 1330 that touches the workpiece is within eight degrees1412 of parallel to the axis of rotation. Alternatively, the first andsecond parts of the path may be within eight degrees of parallel to oneanother.

This device further may include an image processor 1135 that controlsreads from or writes to the workpiece and an image processor thatassembles composite image information 545A-D corresponding to an imageat the workpiece spanning some part of the optical arm's sweep. Forinstance, the image processor may assemble composite image informationthat corresponds to at least five, ten or twenty degrees of sweep. Thecomposite image information may be information read from the workpieceor it may be a map of information to be written to the workpiece or tobe resampled and written to the workpiece.

Of course, the embodiments, implementations, aspects and features of thefirst device above can be combined in numerous ways to produce a varietyof systems. By this statement, we mean to disclose combinations as ifthey were multiply dependent claims, each feature depending from all ofthe preceding features, except where they might be logicallyinconsistent.

A further embodiment provides a low-cost, high throughput opticalprocessing device using one or more optical arms rotating about a hub torelay image information between a hub and the surface of the workpiece,while maintaining a consistent orientation relationship betweeninformation on the workpiece and information at the hub of the opticalarm, even as the arm sweeps an arc across the workpiece 410. Individualoptical arms can have simple optics and be light weight. Multiple armscan be used to increase the duty cycle of relaying information as apercentage of a sweep through a full circle. The features, aspects, etc.described above may be combined in many configurations with this furtherembodiment.

Another embodiment provides a high throughput, low data complexitysystem using one or more optical arms rotating about a hub to relayimage information between a hub and the surface of the workpiece 410,while maintaining a consistent orientation relationship 430, 445A-Bbetween information on the workpiece and information at the hub of theoptical arm, even as the arm sweeps an arc across the workpiece. Imagesseparated in time can be represented as displaced from one another by adisplacement vector, without rotation of the images. Motion of aworkpiece relative to an axis of rotation for the optical arms can alsobe expressed as a displacement vector. The two displacement vectors canbe summed. The rotational speed of the optical arms and relativemovement of the workpiece can be selected to produce a desiredrelationship that impacts overlap between images. The features, aspects,etc. described above may be combined in many configurations with thisother embodiment.

The preceding description has carefully referred to relaying imagesbetween the workpiece and hub because image information can be relayedin either direction. For writing to a workpiece, an SLM, DMD, scanninglaser(s) or other radiation source can be controlled at the hub and therotating arm used to project the image onto the workpiece. Forinspecting or imaging a workpiece, a detector at the hub can be used tocapture an image scanned from the workpiece under an optical componentat the distal end of the arm(s).

Another embodiment comprises a method for scanning a large flatworkpiece to read or write an image 855 on it using a stationary imagedevice 430 having an optical axis (FIGS. 14 a-14 b). The image 855 canbe either prepared or selected. Scan optics, having an entrance near theimage device optical axis and an exit optical axis near the workpiece,are provided. Optical axes can be, essentially, parallel oranti-parallel and aligned with the stationary device having the entranceoptical axis. The present disclosure consists of drawn examplesdepicting 8 degrees difference.

The scan optics are rotated around a rotation axis perpendicular to theworkpiece and geometrically close to the entrance optical axis i.e.,closer or much closer than the exit optical axis. A controller is usedfor controlling rotation by scan optics. Partial images can be read orwritten for different rotation angles. Also, a combined image can bebuilt in the controlling electronics before or after the photons fly.

In one implementation, the image 445 is translated but not rotated whilethe scan optics rotate. Alternatively, the images can rotate and acombined image 545A-D built from partial images rotated relative to eachother.

In another implementation, entry and exit images may have the sameparity. The x and y axes can be scaled and rotated but cannot bereversed. They must be visible from the same side along the light beamif the optical axes are parallel, or along one axis and against theother if they are anti-parallel.

Stationary device may include a laser diode array, a LED array, a 2D SLM1130. A 2D SLM might be a tilting mirror, piston mirror, or DMD device,or an LCD shutter device. A 1D SLM might be a GLV. A scanner could beused, such as an acoustooptic, polygon or, electrooptic scanner. A linecamera, an area camera, a spectrometer, scatterometer or aninterferometer could be used in a system that read from the workpieceinstead of writing to it. Scan optics may include mirrors and lenses.

One embodiment of the disclosed technology uses a rotating or swingingarm that describes an arc across a workpiece as it scans, instead offollowing a traditional straight-line motion. One aspect of thetechnology is that the arm can be placed radially in a rotating disk orrotor and that the rotor can have several arms, e.g. 2, 3, 4, 6, or 8arms, thereby multiplying the scanned surface area per time unit.

Another aspect of the technology is that heavy, complex, fragile machineparts, or parts that are expensive or need many connections and servicescan be placed stationary near the center or hub of the rotor and beshared by the multiple arms.

A further aspect of the technology is that an image is relayed betweenan image device placed stationary near the hub of the rotor and theworkpiece through the radial arm and that the relayed image isnon-rotating, or essentially non-rotating, when the rotor rotates.

It is another aspect of the technology that partial images are createdwhen the rotor rotates and that the partial images are stitched togetherto a continuous curved stripe. Yet another aspect of the disclosedtechnology is that the stitching together of partial images is done withbitmaps which are essentially non-rotating, but where the pixel grid isdisplaced from image to image.

While the disclosed technology is disclosed by reference to thepreferred embodiments and examples detailed above, it is understood thatthese examples are intended in an illustrative rather than in a limitingsense. Computer-assisted processing is implicated in the describedembodiments, implementations and features. Accordingly, the disclosedtechnology may be embodied in methods for reading or writing a workpieceusing at least one optical arm that sweeps an arc over the workpiece,systems including logic and resources to carry out reading or writing aworkpiece using at least one optical arm that sweeps an arc over theworkpiece, systems that take advantage of computer-assisted control forreading or writing a workpiece using at least one optical arm thatsweeps an arc over the workpiece, media impressed with logic to carryout, data streams impressed with logic to carry out reading or writing aworkpiece using at least one optical arm that sweeps an arc over theworkpiece, or computer-accessible services that carry outcomputer-assisted reading or writing a workpiece using at least oneoptical arm that sweeps an arc over the workpiece. It is contemplatedthat modifications and combinations will readily occur to those skilledin the art, which modifications and combinations will be within thespirit of the disclosed technology and the scope of the followingclaims.

We claim as follows:
 1. A method of writing to or reading from aworkpiece, the method including: using a stationary optical image deviceto form or collect relayed image information; relaying the imageinformation along optics of at least one rotating arm between thestationary optical image device and a surface of the workpiece;repeatedly sweeping a curved stripe across the surface of the workpieceto write or read a contiguous image formed from overlapping images thatare stitched together; and relaying the pattern information between theoptical image device and the surface with a substantially constantazimuthal orientation, wherein the azimuthal orientation of the relayedimage information is substantially constant when a set image at theoptical image device maintains a constant angular relationship torelayed versions of the set image on the workpiece with no more than a0.5 degree rotational variation in the angular relationship when therelayed versions are separated by 5 degrees sweep of the optical arm. 2.The method of claim 1, further including determining the grid of eachoverlapping image and converting the image between its own grid and acommon reference grid by image processing.
 3. The method of claim 1,wherein the set image at the optical image device maintains a constantangular relationship to relayed versions of the set image on theworkpiece with no more than a 0.5 degree rotational variation in theangular relationship when the relayed versions are separated by 45degrees sweep of the optical arm.
 4. The method of claim 1, wherein therelaying the image information further includes traversing a firstoptical axis coupled to the stationary optical image device andpositioned at or near an axis of rotation of the rotating arm; andtraversing a second optical axis coupled to the surface and positioneddistally along the rotating arm from the axis of rotation.
 5. The methodof claim 4, wherein the first and second optical axis are substantiallyparallel or anti-parallel to each other within about eight degrees. 6.The method of claim 5, wherein the second optical axis is at least tentimes as far from the axis of rotation as the first optical axis.
 7. Themethod of claim 5, further including preserving optical parity of therelayed image information when the first and second optical axes aresubstantially parallel.
 8. The method of claim 5, further includingreversing optical parity of the relayed image information when the firstand second optical axes are substantially anti-parallel.
 9. The methodof claim 1, wherein the optical image device forms an image that isrelayed to the workpiece.
 10. The method of claim 1, wherein the opticalimage device that forms the image is a spatial light modulator (SLM).11. The method of claim 1, wherein the optical image device that formsthe image is an array of writing beams.
 12. The method of claim 1,wherein the optical image device detects an image that is relayed fromthe workpiece.
 13. The method of claim 12, where there are two or moreoptical image device of different types.
 14. The method of claim 13,wherein at least one optical image device emits an exciting beam throughan arm and receives an image back from the workpiece.
 15. The method ofclaim 14, further including determining the grid of each part of thecontiguous image and converting the part of the contiguous image betweenits own grid and the grid of the contiguous image.
 16. The method ofclaim 15, wherein the part of the contiguous image is a partial image.17. The method of claim 1, wherein the relayed image information isrelayed in a pulsed series of stamps.
 18. The method of claim 1, whereinthe relayed image information is relayed in a substantially continuoussweep.
 19. An optical scanning device that writes to or reads from aworkpiece, the device including: at least one optical arm rotating abouta hub and having an axis of rotation; a stage on which the workpiece ispositioned, which is perpendicular to the axis of rotation; a stationaryoptical image device; relay optics that relay image information alongthe optical arm, between the stationary optical image device and asurface of the workpiece; and an image processor that assembles acontiguous image corresponding to the image information relayed as therotating arm sweeps over parts of the surface, wherein the imageprocessor either, in a writing device, writes parts of the contiguousimage onto the surface to form a contiguous curved stripe; or in areading device, reads parts of the contiguous image from a contiguouscurved stripe on the surface and stitches the parts together in memoryto form the contiguous image; wherein the relay optics relay the patterninformation between the optical image device and the surface with asubstantially constant azimuthal orientation, wherein the azimuthalorientation of the relayed image information is substantially constantwhen a set image at the optical image device maintains a constantangular relationship to relayed versions of the set image on theworkpiece with no more than a 0.5 degree rotational variation in theangular relationship when the relayed versions are separated by 5degrees sweep of the optical arm.
 20. The device of claim 19, whereinthe optical image device maintains a constant angular relationship torelayed versions of the set image on the workpiece with no more than a0.5 degree rotational variation in the angular relationship when therelayed versions are separated by 45 degrees sweep of the optical arm.21. The device of claim 19, further including: a first optical axis ofthe relay optics, coupled to the stationary optical image device andpositioned at or near an axis of rotation of the rotating arm; and asecond optical axis of the relay optics, coupled to the surface andpositioned distally along the rotating arm from the axis of rotation.22. The device of claim 21, wherein the first and second optical axesare substantially parallel or anti-parallel to each other within abouteight degrees.
 23. The device of claim 22, wherein the second opticalaxis is at least ten times as far from the axis of rotation as the firstoptical axis.
 24. The device of claim 22, wherein the relay opticspreserve optical parity of the relayed image information when the firstand second optical axes are substantially parallel.
 25. The device ofclaim 22, wherein the relay optics reverse optical parity of the relayedimage information when the first and second optical axes aresubstantially anti-parallel.
 26. The device of claim 19, wherein theoptical image device forms an image that is relayed to the workpiece.27. The device of claim 26, wherein the optical image device that formsthe image is any one of a spatial light modulator (SLM), grating lightvalve (GLV), deformable micromirror device (DMD), or liquid crystaldisplay (LCD).
 28. The device of claim 26, wherein the optical imagedevice that forms the image is any one of a laser diode array or an LEDarray.
 29. The device of claim 26, wherein the optical image device thatforms the image is an array of writing beams.
 30. The device of claim26, wherein the optical image device detects an image that is relayedfrom the workpiece.
 31. The device of claim 26, wherein the opticalimage device is any of a line camera, an area camera, a spectrometer, ascatterometer or an interferometer.
 32. The device of claim 19, whereinthe relayed image information is relayed in a pulsed series of stamps.33. The device of claim 19, wherein the relayed image information isrelayed in a substantially continuous sweep.